1. Field of the Invention
The present invention relates to a method and an apparatus for performing radio monitoring, and more particularly, to a method and an apparatus for performing radio monitoring in a certain area where radio waves are used at a relatively high density to prevent the generation of radio interference.
2. Description of the Prior Art
With development of a mobile communication system, a wireless local area network (LAN) or the like, radio waves are used at a high density in urban areas and limited frequency resources are shared. Consequently, radio interference is generated to the extent that it can not be negligible.
When a radio wave source which causes the radio interference is specified, a sensor station (monitoring station) is conventionally placed in each of a plurality of points, the Yagi-Uda antenna or a goniometer is used in each sensor station to observe a direction in which a radio wave comes from the radio wave source, and the radio wave incoming directions at respective sensor stations are plotted on a map to specify the position of the radio wave source based on the position of an intersection point of the directions.
Since the above-mentioned conventional method specifies the position of the radio wave source based on the intersection point of the incoming directions of the radio wave observed in the sensor stations, at least two sensor stations are required. Thus, this method has a disadvantage that it can specify only a radio wave source of a relatively strong radiation receivable simultaneously at two or more sensor stations. Additionally, when two or more radio wave sources are present at positions near to each other at the same frequency band, radio waves transmitted therefrom can not separated for observation, thereby obtaining a result of observing the incoming radio wave direction in the sensor station in the form of a synthesized radio wave. Thus, it may be impossible to estimate each position of the radio wave source in this case.
The radio interference in urban areas may frequently occur even between radio wave sources which are close to each other and emit relatively weak radio waves. Also, the sensor stations can not be placed at a high density in consideration of costs or the like. Consequently, according to the conventional method, it is impossible to completely specify the generation source of the radio interference and it is extremely difficult to find the cause of the radio interference.